A disorder having a rapid, irregular sequence of heart beats resulting from a disordered electrical excitation of the atria, is known as atrial fibrillation or atrial flutter. A distinction is made between paroxysmal (sudden) and persistent (chronic) arrhythmia. Some of these arrhythmia types may be treated by medications while others must be treated by external cardioversion. For this latter treatment, a high quantity of energy is output through the external area of the body, conventionally under anesthetic to restore the normal cardiac rhythm (sinus rhythm). Several studies have managed to show that the transvenous cardioversion of atrial fibrillation and/or atrial flutter can be performed with a considerably lower energy level than if the energy is applied to the external area of the body.
The use of an energy quantity of 200 J in an initial phase of treatment for external cardioversion and, in the event of its failure, two further pulses of 360 J, is proposed by Gordon A. Ewy as the optimal form of therapy in his article entitled “Optimal Technique for Electrical Cardioversion of Atrial Fibrillation”, Circulation, pp. 1645 ff, Volume 86, No. 5, November 1992. Despite these high levels of energy output, Ewy emphasizes that great care must be given to ensuring the correct positioning and low transfer resistance of the external defibrillation electrodes, to achieve the best results.
As part of a comparative study, Levy et al. report in their publication entitled “A Randomized Comparison of External and Internal Cardioversion of Chronic Atrial Fibrillation”, Circulation, pp. 1415-20, Volume 86, No. 5, November 1992, on the results of external and internal cardioversion and come to the conclusion that internal cardioversion is more effective for the restoration of the sinus rhythm without involving any increased risks. Internal cardioversion was completed for this study using a catheter fitted with an electrode together with an external thorax electrode.
E. Alt, C. Schmitt, R. Ammer, M. Coenen, P. Fotuhi, M. Karch and R. Blasini present a method of therapy for treating arrhythmia in their article entitled “Initial Experience with Intracardiac Atrial Defibrillation in Patients with Chronic Atrial Fibrillation”, PACE, Volume 17, May 1994, Part II, in which an initial catheter fitted with a distal electrode is inserted in the Coronary Sinus in a catheter laboratory with X-ray monitoring, and a second catheter, also fitted with a distal electrode, is positioned in the right atrium. With this form of therapy, too, low levels of energy were used to remedy both spontaneous as well as induced atrial fibrillation, essentially with no negative effects.
Although the transvenous forms of therapy are not only far superior in terms of the levels of output energy compared to methods which use externally applied electrodes, there have been major effects to achieve further improvements in the therapy and in the equipment used for it.
A process of this nature in clinical emergency should provide extremely short preparation times and place as little stress as possible on the patient. Furthermore, the safety involved with this type of therapy should be increased. Although costs are of lesser importance in this particular area, they are becoming increasingly significant recently as a result of the wide range of efforts to make savings.